/* pnmrotate.c - read a portable anymap and rotate it by some angle
**
** Copyright (C) 1989, 1991 by Jef Poskanzer.
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation.  This software is provided "as is" without express or
** implied warranty.
*/

#include <math.h>
#include "pnm.h"
#ifndef M_PI
#define M_PI    3.14159265358979323846
#endif /*M_PI*/

#define SCALE 4096
#define HALFSCALE 2048

int
main(int argc, char *argv[]) { 
    FILE* ifp;
    xel* xelrow;
    xel** temp1xels;
    xel** temp2xels;
    xel* newxelrow;
    register xel* xP;
    register xel* nxP;
    xel bgxel, prevxel, x;
    int argn, rows, cols, format, newformat, newrows;
    int tempcols, newcols, yshearjunk, x2shearjunk, row, col, new;
    xelval maxval, newmaxval;
    int antialias;
    float fangle, xshearfac, yshearfac, new0;
    int intnew0;
    register long fracnew0, omfracnew0;
    const char* const usage = "[-noantialias] <angle> [pnmfile]";

    pnm_init( &argc, argv );

    argn = 1;
    antialias = 1;

    if ( argn < argc && argv[argn][0] == '-' && argv[argn][1] != '\0' &&
         ( argv[argn][1] < '0' || argv[argn][1] > '9' ) ) {
        if ( pm_keymatch( argv[argn], "-antialias", 2 ) )
            antialias = 1;
        else if ( pm_keymatch( argv[argn], "-noantialias", 2 ) )
            antialias = 0;
        else
            pm_usage( usage );
        ++argn;
    }

    if ( argn == argc )
        pm_usage( usage );
    if ( sscanf( argv[argn], "%f", &fangle ) != 1 )
        pm_usage( usage );
    ++argn;
    if ( fangle < -90.0 || fangle > 90.0 )
        pm_error( "angle must be between -90 and 90" );
    fangle = fangle * M_PI / 180.0; /* convert to radians */

    xshearfac = tan( fangle / 2.0 );
    if ( xshearfac < 0.0 )
        xshearfac = -xshearfac;
    yshearfac = sin( fangle );
    if ( yshearfac < 0.0 )
        yshearfac = -yshearfac;

    if ( argn != argc ) {
        ifp = pm_openr( argv[argn] );
        ++argn;
    } else
        ifp = stdin;

    if ( argn != argc )
        pm_usage( usage );

    pnm_readpnminit( ifp, &cols, &rows, &maxval, &format );
    xelrow = pnm_allocrow( cols );

    /* Promote PBM files to PGM. */
    if ( antialias && PNM_FORMAT_TYPE(format) == PBM_TYPE ) {
        newformat = PGM_TYPE;
        newmaxval = PGM_MAXMAXVAL;
        pm_message( "promoting from PBM to PGM - "
                    "use -noantialias to avoid this" );
    } else {
        newformat = format;
        newmaxval = maxval;
    }

    tempcols = rows * xshearfac + cols + 0.999999;
    yshearjunk = ( tempcols - cols ) * yshearfac;
    newrows = tempcols * yshearfac + rows + 0.999999;
    x2shearjunk = ( newrows - rows - yshearjunk ) * xshearfac;
    newrows -= 2 * yshearjunk;
    newcols = newrows * xshearfac + tempcols + 0.999999 - 2 * x2shearjunk;

    bgxel = pnm_backgroundxelrow( xelrow, cols, newmaxval, format );

    /* First shear X into temp1xels. */
    temp1xels = pnm_allocarray( tempcols, rows );
    for ( row = 0; row < rows; ++row ) {
        pnm_readpnmrow( ifp, xelrow, cols, newmaxval, format );
        if ( fangle > 0 )
            new0 = row * xshearfac;
        else
            new0 = ( rows - row ) * xshearfac;
        intnew0 = (int) new0;
        
        if ( antialias ) {
            fracnew0 = ( new0 - intnew0 ) * SCALE;
            omfracnew0 = SCALE - fracnew0;
            
            for ( col = 0, nxP = temp1xels[row]; col < tempcols; ++col, ++nxP )
                *nxP = bgxel;
            
            prevxel = bgxel;
            for ( col = 0, nxP = &(temp1xels[row][intnew0]), xP = xelrow;
                  col < cols; ++col, ++nxP, ++xP ) {
                switch ( PNM_FORMAT_TYPE(format) )
                {
                case PPM_TYPE:
                    PPM_ASSIGN( *nxP,
                                ( fracnew0 * PPM_GETR(prevxel) 
                                  + omfracnew0 * PPM_GETR(*xP) 
                                  + HALFSCALE ) / SCALE,
                                ( fracnew0 * PPM_GETG(prevxel) 
                                  + omfracnew0 * PPM_GETG(*xP) 
                                  + HALFSCALE ) / SCALE,
                                ( fracnew0 * PPM_GETB(prevxel) 
                                  + omfracnew0 * PPM_GETB(*xP) 
                                  + HALFSCALE ) / SCALE );
                    break;
                    
                default:
                    PNM_ASSIGN1( *nxP,
                                 ( fracnew0 * PNM_GET1(prevxel) 
                                   + omfracnew0 * PNM_GET1(*xP) 
                                   + HALFSCALE ) / SCALE );
                    break;
                }
                prevxel = *xP;
            }
            if ( fracnew0 > 0 && intnew0 + cols < tempcols ) {
                switch ( PNM_FORMAT_TYPE(format) ) {
                case PPM_TYPE:
                    PPM_ASSIGN( *nxP,
                                ( fracnew0 * PPM_GETR(prevxel) 
                                  + omfracnew0 * PPM_GETR(bgxel) 
                                  + HALFSCALE ) / SCALE,
                                ( fracnew0 * PPM_GETG(prevxel) 
                                  + omfracnew0 * PPM_GETG(bgxel) 
                                  + HALFSCALE ) / SCALE,
                                ( fracnew0 * PPM_GETB(prevxel) 
                                  + omfracnew0 * PPM_GETB(bgxel) 
                                  + HALFSCALE ) / SCALE );
                    break;
                    
                default:
                    PNM_ASSIGN1( *nxP,
                                 ( fracnew0 * PNM_GET1(prevxel) 
                                   + omfracnew0 * PNM_GET1(bgxel) 
                                   + HALFSCALE ) / SCALE );
                    break;
                }
            }
        } else {
            for ( col = 0, nxP = temp1xels[row]; col < intnew0; ++col, ++nxP )
                *nxP = bgxel;
            for ( col = 0, xP = xelrow; col < cols; ++col, ++nxP, ++xP )
                *nxP = *xP;
            for ( col = intnew0 + cols; col < tempcols; ++col, ++nxP )
                *nxP = bgxel;
        }
    }
    pm_close( ifp );
    pnm_freerow( xelrow );
    
    /* Now inverse shear Y from temp1 into temp2. */
    temp2xels = pnm_allocarray( tempcols, newrows );
    for ( col = 0; col < tempcols; ++col ) {
        if ( fangle > 0 )
            new0 = ( tempcols - col ) * yshearfac;
        else
            new0 = col * yshearfac;
        intnew0 = (int) new0;
        fracnew0 = ( new0 - intnew0 ) * SCALE;
        omfracnew0 = SCALE - fracnew0;
        intnew0 -= yshearjunk;
        
        for ( row = 0; row < newrows; ++row )
            temp2xels[row][col] = bgxel;
        
        if ( antialias ) {
            prevxel = bgxel;
            for ( row = 0; row < rows; ++row ) {
                new = row + intnew0;
                if ( new >= 0 && new < newrows ) {
                    nxP = &(temp2xels[new][col]);
                    x = temp1xels[row][col];
                    switch ( PNM_FORMAT_TYPE(format) ) {
                    case PPM_TYPE:
                        PPM_ASSIGN( *nxP,
                                    ( fracnew0 * PPM_GETR(prevxel) 
                                      + omfracnew0 * PPM_GETR(x) 
                                      + HALFSCALE ) / SCALE,
                                    ( fracnew0 * PPM_GETG(prevxel) 
                                      + omfracnew0 * PPM_GETG(x) 
                                      + HALFSCALE ) / SCALE,
                                    ( fracnew0 * PPM_GETB(prevxel) 
                                      + omfracnew0 * PPM_GETB(x) 
                                      + HALFSCALE ) / SCALE );
                        break;
                        
                    default:
                        PNM_ASSIGN1( *nxP,
                                     ( fracnew0 * PNM_GET1(prevxel) 
                                       + omfracnew0 * PNM_GET1(x) 
                                       + HALFSCALE ) / SCALE );
                        break;
                    }
                    prevxel = x;
                }
            }
            if ( fracnew0 > 0 && intnew0 + rows < newrows ) {
                nxP = &(temp2xels[intnew0 + rows][col]);
                switch ( PNM_FORMAT_TYPE(format) ) {
                case PPM_TYPE:
                    PPM_ASSIGN( *nxP,
                                ( fracnew0 * PPM_GETR(prevxel) 
                                  + omfracnew0 * PPM_GETR(bgxel) 
                                  + HALFSCALE ) / SCALE,
                                ( fracnew0 * PPM_GETG(prevxel) 
                                  + omfracnew0 * PPM_GETG(bgxel) 
                                  + HALFSCALE ) / SCALE,
                                ( fracnew0 * PPM_GETB(prevxel) 
                                  + omfracnew0 * PPM_GETB(bgxel) 
                                  + HALFSCALE ) / SCALE );
                    break;
                    
                default:
                    PNM_ASSIGN1( *nxP,
                                 ( fracnew0 * PNM_GET1(prevxel) 
                                   + omfracnew0 * PNM_GET1(bgxel) 
                                   + HALFSCALE ) / SCALE );
                    break;
                }
            }
        } else {
            for ( row = 0; row < rows; ++row ) {
                new = row + intnew0;
                if ( new >= 0 && new < newrows )
                    temp2xels[new][col] = temp1xels[row][col];
            }
        }
    }
    pnm_freearray( temp1xels, rows );
    
    /* Finally, shear X from temp2 into newxelrow. */
    pnm_writepnminit( stdout, newcols, newrows, newmaxval, newformat, 0 );
    newxelrow = pnm_allocrow( newcols );
    for ( row = 0; row < newrows; ++row ) {
        if ( fangle > 0 )
            new0 = row * xshearfac;
        else
            new0 = ( newrows - row ) * xshearfac;
        intnew0 = (int) new0;
        fracnew0 = ( new0 - intnew0 ) * SCALE;
        omfracnew0 = SCALE - fracnew0;
        intnew0 -= x2shearjunk;

        for ( col = 0, nxP = newxelrow; col < newcols; ++col, ++nxP )
            *nxP = bgxel;
        
        if ( antialias ) {
            prevxel = bgxel;
            for ( col = 0, xP = temp2xels[row]; col < tempcols; ++col, ++xP ) {
                new = intnew0 + col;
                if ( new >= 0 && new < newcols ) {
                    nxP = &(newxelrow[new]);
                    switch ( PNM_FORMAT_TYPE(format) ) {
                    case PPM_TYPE:
                        PPM_ASSIGN( *nxP,
                                    ( fracnew0 * PPM_GETR(prevxel) 
                                      + omfracnew0 * PPM_GETR(*xP) 
                                      + HALFSCALE ) / SCALE,
                                    ( fracnew0 * PPM_GETG(prevxel) 
                                      + omfracnew0 * PPM_GETG(*xP) 
                                      + HALFSCALE ) / SCALE,
                                    ( fracnew0 * PPM_GETB(prevxel) 
                                      + omfracnew0 * PPM_GETB(*xP) 
                                      + HALFSCALE ) / SCALE );
                        break;

                    default:
                        PNM_ASSIGN1( *nxP,
                                     ( fracnew0 * PNM_GET1(prevxel) 
                                       + omfracnew0 * PNM_GET1(*xP) 
                                       + HALFSCALE ) / SCALE );
                        break;
                    }
                    prevxel = *xP;
                }
            }
            if ( fracnew0 > 0 && intnew0 + tempcols < newcols ) {
                nxP = &(newxelrow[intnew0 + tempcols]);
                switch ( PNM_FORMAT_TYPE(format) ) {
                case PPM_TYPE:
                    PPM_ASSIGN( *nxP,
                                ( fracnew0 * PPM_GETR(prevxel) 
                                  + omfracnew0 * PPM_GETR(bgxel) 
                                  + HALFSCALE ) / SCALE,
                                ( fracnew0 * PPM_GETG(prevxel) 
                                  + omfracnew0 * PPM_GETG(bgxel) 
                                  + HALFSCALE ) / SCALE,
                                ( fracnew0 * PPM_GETB(prevxel) 
                                  + omfracnew0 * PPM_GETB(bgxel) 
                                  + HALFSCALE ) / SCALE );
                    break;
                    
                default:
                    PNM_ASSIGN1( *nxP,
                                 ( fracnew0 * PNM_GET1(prevxel) 
                                   + omfracnew0 * PNM_GET1(bgxel) 
                                   + HALFSCALE ) / SCALE );
                    break;
                }
            }
        } else {
            for ( col = 0, xP = temp2xels[row]; col < tempcols; ++col, ++xP ) {
                new = intnew0 + col;
                if ( new >= 0 && new < newcols )
                    newxelrow[new] = *xP;
            }
        }

        pnm_writepnmrow( stdout, newxelrow, newcols, newmaxval, newformat, 0 );
    }

    pm_close( stdout );
    
    exit( 0 );
}

